1. Field of the Invention
The present invention relates to an object detection device that irradiates an object to be measured with measurement light having a predetermined pattern and detects the object to be measured based on reflected light of the measurement light.
2. Description of the Related Art
In a three-dimensional measurement device disclosed in Japanese Patent No. 5001286, an illumination area is irradiated with a random speckle pattern in which a large number of spot lights generated by a light source are arranged at random, and the light response of the illumination area is detected by an image sensor. Displacement of the speckle pattern is detected in a pattern image obtained when the object to be measured has moved to the illumination area and a reference image of the random speckle pattern when there is no object to be measured, and a three-dimensional map of the object to be measured is constructed using a three-dimensional measurement method. When the three-dimensional map is constructed as above, an imaging unit repeats scanning line by line from one end of the illumination area according to a raster scan scheme to obtain a captured image of the entire illumination area, calculates the displacement of the speckle pattern, and constructs a three-dimensional map of the object to be measured. Further, by comparing the constructed three-dimensional maps in time series, it is possible to calculate a speed at which the object to be measured has moved within the illumination area.
In an object detection device described in Japanese Unexamined Patent Application Publication No. 2014-48124, a configuration in which pupil directions of a light source and an image sensor are made in parallel with each other when a three-dimensional map of an object to be measured is constructed, such that a displacement direction of a speckle pattern is limited to a direction in one axial direction (X-axis) is disclosed. Thus, an amount of displacement of the object to be measured can be calculated by detecting only the displacement along the X-axis and, accordingly, a calculation process can be simplified.
However, in the three-dimensional measurement device disclosed in Japanese Patent No. 5001286, when a movement speed of the object to be measured is calculated, it is necessary to continue to compare three-dimensional maps constructed at predetermined time intervals, each time, and accordingly, a processing load is very high.
Further, even when calculation of the amount of displacement is simplified using the object detection device of Japanese Unexamined Patent Application Publication No. 2014-48124, the three-dimensional map is still used to calculate the movement speed, and accordingly, the processing load is still high.
In particular, in order to accurately construct a three-dimensional map of the object to be measured, it is necessary to increase the number of speckle patterns and densify the speckle patterns. Therefore, an amount of spot lights to be compared on a time axis greatly increases in calculation of a movement speed, and a processing load increases. As a result, when the movement speed of the object to be measured is high, processing cannot keep up and the speed cannot be detected.